MDL-37804 assign: Return proper notice when submissions closed.

MDL-38267 was returning the html page when it should have been adding to the list
of notices and returing false.
MDL-21415 reports: We should fetch active group from session not page params

Also donot allow active group to be set to something that user doesn't have access to
MDL-38570 admin: fix cron_delete_from_temp on windows
MDL-41238 atto - fixing autoclose of style menu for firefox
MDL-41555 behat: Fixing catch statement location

The exception is thrown when getting the
browser session, not when accessing the first
URL.
MDL-41305 group: Behat test failing due to string change
Revert "MDL-40829: courses heading: remove 'headerblock' class from header and fix heading levels"

This reverts commit 278d64572d272c776c564dcd743959c21ee20c8b.

Conflicts:
	theme/bootstrapbase/style/moodle.css
NOBUG/MDL-40829 - fix whitespace errors